LDMOS (Laterally Diffused MOSFET) devices find wide applications in high power or high voltage circuits, such as for example switching DC-to-DC voltage converters. A STI (Shallow Trench Isolation) region is usually formed in the drift layer of an LDMOS. For good performance, it is important that an LDMOS not exhibit hot carrier shifts, where for example electrons in an n-channel LDMOS are injected into the STI region. Furthermore, in many applications, it is desirable for an LDMOS to operate in high voltage environments, and yet still have relatively low ON resistance.